Electronic ignition/Capacitor discharge ignition (CDI)

Electronic ignition/Capacitor discharge ignition (CDI)

Today, engines have an electronic ignition system known as capacitor discharge ignition (CDI) and modules may fail, requiring replacement. If the ignition coil does not produce a spark after testing a new Plug and has checked the power switch to make sure it is not short-circuited, there is nothing else you can do but replace the module.

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Wiring and connections lawn mower

Wiring and connections lawn mower

If a spark is not obtained, inspect the motor wiring. As in a car, the ignition system uses the engine block as a ground, so make sure all the ring notches are tight and not loose. Damaged insulation can short-circuit the voltage to the engine block. The swords can be detached, and the screws holding the ring can be loosened due to vibration.
Check for loose or dirty connections.

The Kill Switch

If you still can't produce a spark, there might be a problem on the kill switch. This shuts off the motor by shorting the magneto coil and prevents a spark from being created when the mower is turned off. The switch works when you release the "Dead Handle" on the mower or put the throttle in the stop position. Trace The wire on the magneto coil to find this switch. You will most likely need to remove the hood from the top of the engine and possibly the steering wheel to check this.

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Check the switch using the continuity or lowest ohm range on your meter. The switch must be in the open circuit when the engine is running and there is a shorting when the motor is off. Remove one of the connections to the switch when checking. Otherwise, the resistance of the magneto coil will give a false reading.

The ignition system: the best place to start troubleshooting

The ignition system: the best place to start troubleshooting

The function of the ignition system is to create a spark on the plug and Ignite the fuel/air mixture in the cylinder. A device called Magneto generates high voltage, and any of the mechanically operated points or an electronic switch will trigger the spark at the appropriate time in the four-stroke cycle.

More than 90% of the time, problems with gas engines are due to a carburetor problem. However, the spark plug is easy to check first.

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See the ignition system diagram below.
The Magneto

On a push mower and other battery-free motors (such as chainsaws, trimmers, and motorcycles without batteries), a device called Magneto is used to generate the high-voltage spark. Magnets are even used on aircraft with a piston motor for safety reasons, so the failure of the battery or alternator does not cause the engine to cut. A magneto is a sort of crossover between a generator and a transformer and has a primary and secondary coil.

The magnet is mounted by the steering wheel (the thing with fins on top of the mower, which rotates). A magnet embedded in the edge of the flywheel induces a current pulse on the primary coil as it moves rapidly beyond the magneto poles. When the current reaches a peak, a set of switch contacts called points is opened, interrupting the current. This causes the magnetic field in the primary coil to collapse rapidly, causing a voltage spike in the secondary coil. This coil, which has many cable turns, increases the voltage to approximately 10,000 volts (or more). A capacitor, also known as condenser, absorbs the current produced by the primary coil allowing the magnetic field to collapse rapidly. The modern engines have electronic ignition and the points are replaced by an electronic switch called thyristor or SCR (silicon-controlled rectifier).

1. Some engines (such as those used in the ride mowers) do not have magnets, and instead will use an on-board battery and a ignition coil to produce a spark, similar to a car's system.
2. Schematic of lawnmower ignition circuit with mechanical points. The points are connected to the primary of the magneto, the spark plug to the secondary.
3. Diagram of the lawnmower's ignition circuit with mechanical points. The dots are connected to the magnet's primary, the spark plug to the secondary.
4. Modern engines have electronic ignition and there are no points to clean. If the ignition module fails, the complete unit needs to be replaced.
5. Modern engines have electronic ignition and there are no points to clean. If the ignition module fails, the entire unit must be replaced.
6. Engine flywheel, visible when the cowling or cover over the mower is removed.
7. Motor flywheel, visible when the fairing or cover is removed on the mower.
8. Flywheel, magneto, and governor vane.
9. Steering wheel, Magneto and governor's paddle.
10. Spark Test on Plug

•     First, verify that the wire that feeds high voltage to the spark plug should not be loose and must be snug. Sometimes the cable may come out of the rubber sheath and the terminal that pushes toward the spark plug. Then, using a spark plug wrench, remove the plug, replace the plug cable into the plug, and place the threaded part of the plug in contact with the motor block to ground it.
•     Now pull the starter cable and look for a spark. You must keep the plug tight against the motor in some way, as it may bounce when you pull the starter cord. This is where an assistant can be useful as it can be difficult for you to see the plug from where you are pulling the starter cable. Try pressing the plug against the lawn mower with a plastic piece or similar, such as a plastic garment peg. The cable could hold the plug, but if it is wet or if the insulation is bad, you may end up getting shocked!
•     If you do not see a spark at this point, there may be a crack in the stopper insulation or it may be dirty and should be cleaned with an old toothbrush and a little gasoline. A wire brush the size of a toothbrush is even better. Let it dry and try to light a spark again. If you are not successful, try another plug and check again. It does not hurt to have a replacement plug for this purpose or to use a car plug, but do not use this plug on the motor unless it is the correct type, as it could hit the piston and cause damage if it is too long.
•     The external electrode of the plug must be filled with a small file if it has been rounded. The spark plug space should usually be adjusted to 0.030 "(30 thousandths of an inch)/0.75 mm, but check your engine manufacturer's recommendations. The separation is measured by a thickness gauge (see photo below). These are generally in the form of a set of steel strips of varying thickness of approximately 0, 002 inches to 0, 030 inches.

    Caution: The threads on a plug are steel, but the engine block and cylinder head are usually aluminum alloys, which is smoother than steel. So that the threads can be damaged if you are not careful. Check for dust or other particles on the plug or motor threads before screwing. Make sure the plug does not kink and do not overtighten. Ideally, you must use a torque wrench to tighten the cap or when you replace the blade on a lawnmower.

If you damage the threads and the plug does not tighten, you can obtain a Helicoil installed in a repair shop. This involves hitting the stock and screwing an insert into place that has internal threads to fit the plug.

If the starter cable is difficult to pull, slip or roll

If the starter cable is difficult to pull, slip or roll

If you find it difficult to remove the starter cord, there are three possible causes:

•     First, groups of wet grass or moss can clog the bottom of the platform and prevent the blade from spinning. Before removing clippings and attempting to rotate the blade to clear the platform, disconnect the spark plug wire.
•     The flywheel brake may prevent the motor from turning. When you release the "Dead Man's Handle" on the mower handle, a switch shuts off and shuts off the engine. A brake is also triggered in place and reduces engine speed. If this brake has been seized in place or the cable that operates it has been broken, this will prevent the motor from turning. You will need to remove the fairing at the top of the motor to get this brake.
•     Recoil starters on some engines have approximately half a dozen steel balls that act as part of the ratchet mechanism. These can rust and cause the starter motor to slide and do not start the engine or prevent it from rolling properly. You can clean the balls with fine-wire wool: Add a light jet of oil to the machine in the compartment housing the balls when replacing them. (Scroll down for instructions.)

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Lawn mower adjustment and Troubleshooting: Basic Hand Tools required

Lawn mower adjustment and Troubleshooting: Basic Hand Tools required

•     Set of tube keys. Inch sizes for American and metric engines for European or Japanese engines. You don't need to spend a fortune on a game because you're not going to use it every day. However, do not buy waste because you can use them to work on other equipment. A 3/8 inch ratchet is fine, or a smaller size of 1/4 inch for use in confined spaces.
•     The combined Keys, open at one end and the ring at the other end, are also useful. These can be used for situations in which a nut needs to be undone, but the threaded section of the screw extends too far beyond the nut to fit into a socket. The keys are also known as spanners in the UK. It is not necessary that the sockets or keys are greater than 3/4 of inch AF (in the planes) or 19 mm of size.
•     Plug wrench to remove spark plugs.
•     Screwdrivers. Flat head and Philips, both large and small.
•     Magnetic Tray This is useful to prevent all those small parts from coming out without authorization!
•     Torque Wrench to tighten the bolt that holds the blade and spark plug.
•     Thickness gauge to check the distance between the spark plugs or the dots.

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Note: Tuning an engine refers to the engine adjustment process for optimum performance. This includes adjusting the spark plug and point gap and adjusting the fuel/air mixture and idling speed.

• Combination wrenches (spanners) - Open at one end and ring at the other
• Combined keys (spanners): Open at one end and ring on the other
• Long nose pliers, flat blade screwdriver, Philips screwdriver, and socket wrench.
• Long-nosed pliers, flat-tip screwdriver, Philips screwdriver and socket wrench.
• Two styles of plug wrench: Socket wrench and box wrench/spanner.
• Two styles of pin wrench: socket wrench and box spanner/spanner.

Before dismantling

Before you begin to dismantle everything, take some high resolution photos with a digital camera if there is any chance that you forget to forget how to reassemble the pieces.

In addition, if you need to remove many washers, bushings, springs and nuts on an axle or bolt, you can thread them into a piece of cable to track the reassembly sequence.

Starting your lawnmower: initial troubleshooting checklist

Starting your lawnmower: initial troubleshooting checklist

Tip

• # 1 Use fresh gas. Do not use old gasoline that may cause difficulty starting. Make sure there is enough fuel in the tank and check that the vent on the tank cap is unlocked.
• # 2 Make sure the spark cable is firmly attached to the Plug and the plug is securely screwed. Try replacing the spark plug with a new one.
• # 3 Make sure the "Dead Man" control on the mower is kept fully against the mower handle during startup.
• # 4 Activate choke if a manual choke is installed. Do not turn the choke on if the engine has been running for the last 5 minutes.
• # 5 Be sure to press the primer bulb about 5 times (if applicable). If the mower is running out of gas during cutting, you will need to prime again.
• # 6 Check that the air filter is not dirty. Wash and dry a foam-type air filter (see below for details), or replace a dirty paper filter.
• # 7 Check that the cord connecting the "dead Man's Handle" (on the frame) with the motor is not damaged or broken.
• # 8 Check that the carburetor is properly screwed or screwed to the motor.
• # 9 Make sure there is no water in the bottom of the fuel tank.
• # 10 If the starter cable is difficult to remove, check that there are no grass groups that obstruct the bottom of the platform. These can clog the blade. Unplug the spark plug before attempting to move the blade to remove clippings.

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What happens if my lawnmower still doesn't start?

Scroll down to learn more about how your machine works and other troubleshooting tips.

Protecting Your hands

Ideally, you should wear gloves to protect your hands from dirt that can irritate sensitive skin, especially if you have to change the engine oil or if your hands are in contact with gasoline or diesel. Disposable latex gloves are not recommended, and vinyl gloves are supposed to have only "fair" resistance to petrol/oils, according to specifications. From experience, I have discovered that vinyl disposables appear to be much more durable than latex, and resist contact with oil, grease and gasoline for short periods. Nitrile rubber gloves are the most resistant to these chemicals.

If you dispense with gloves and work with bare hands (which inevitably happens because it is difficult to handle small pieces with gloves), a hand cleaner will do a better job than soap to remove dirt.

Lawn mower Oil Check

Lawn mower Oil Check

Oil level should be between the high and low marks on the dipstick.
The oil level must be between the high and low marks on the level rod.

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Reasons and solutions for a lawn mower that won't start

Why your mower will not start     Possible      solutions

• The engine is not getting the fuel it needs.    Empty and re-fill the tank with fresh gas; Check fuel inlet system: carburetor canister; Choke, throttle, choke button, fuel filter
• He's not getting the spark he needs.    Clean the spark plug, check its connections or replace it; Check the ignition system.
• Needs oil    Check the oil level. Some newer engines have a low oil level floating switch to turn off the start
• He's not getting the air he needs.    Check, clean, or replace the air filter.
• Problems with the starter rope.    Check the flywheel brake; Make sure there is nothing clogging the blade.
• You put diesel in the engine instead of gasoline    Did you really use gasoline? It can detect by smell if fuel is diesel, kerosene or gas. Ask someone who knows the difference.
• Other.    Then you will find many more causes and possible solutions.
• You will then find detailed instructions for troubleshooting and solving all of these problems.

The golden rule of problem solving

Remember to do just one change at a time and try to start over, because if you don't, your first bright spark of inspiration can solve the problem and the second silly idea can make things work again.

How to check the level of oil in a lawn mower

How to check the level of oil in a lawn mower

Lawnmower engines are usually 4-stroke, although 2-stroke engines are available. A 4-stroke engine has a crankcase located at the lowest point of the engine. The oil in this tank is thrown on the walls of the cylinder, the crankshaft and all other moving parts with a dashboard or "flicker". The oil level in an engine must be checked before use. If the level is too low or there is no oil in the motor, it will seize quickly.

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•     Make sure the engine is cold or wait 5 minutes for the oil to stabilize if the engine has been running.
•     Place mower on a level surface.
•     Remove the dipstick: it is usually attached to a small screw cap, smaller than the fuel tank.
•     Clean the rod with a cloth. Consider the high and low level marks.
•     Replace the measuring rod.
•     Now remove the dipstick again and check that the level is between the marks.

Acquire the habit of checking the oil level regularly. Ideally, this should be done every time you use the lawnmower, but if the engine is not burning oil, one control is sufficient each month (depending on use). If cutting in sloping terrain, oil consumption may be higher if oil is expelled through a vent/deflector arrangement for the crankcase called a vent. In fact, it is not harmful to keep the carburetor on the high side when working on a slope.

Lawn mowers should have an oil change after every 20 to 50 hours of use (see your manual or search engine block for more information). If you do not know how to do this, refer to my guide how to change mower oil.

If you buy a new lawnmower or engine, the oil sump will usually be empty. The manufacturers drain the oil after the test and before shipment so that it does not leak if the boxes/boxes are turned upside down. Do not forget to add oil before use! Usually there is a label to remind you to do this before you begin.

How do you start a lawn mower? Correct start procedure

How do you start a lawn mower? Correct start procedure

    Fill the gas tank with a funnel to avoid spilling gas on the engine (spilled gas could ignite if the engine is hot, so ideally wait until it cools).

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    Check oil level as described below.

•     Use new fuel. Old fuel may make it difficult to start, especially fuel containing ethanol that attracts moisture and can cause corrosion. As the fuel evaporates, you can leave a deposit of rubber, gel or varnish that can clog or glue moving parts. Use a fuel stabilization product such as STA-BIL to keep fuel fresh during storage. Once you have the lawnmower running, you can add the old fuel to the fuel in the tank, little by little during the season to use it.
•     The throttle control must be set to the full revolution position. The motors have a device called choke (basically a plate that acts as a blockage in the air inlet) which makes the fuel vapor sucked into the engine "richer" or more concentrated, and this helps to begin. In some cutters, the choke is completely automatic and shuts off when the engine runs for a few seconds. On other mowers, the throttle must be set to an initial start/choke position that ignites the choke mechanism. Once the engine starts, the throttle control returns to the Operation setting. A third scenario is that the choke is completely manual and must be turned on. Usually there is a small lever to do this that should slide into position. This is often the case with portable generators. If a choke is separate, turn it on when starting a cold engine and turn it off after the engine has been running for approximately 5 seconds. Do not use the choke if the engine has been running for the last 10 minutes or so.
•     If the motor has a choke button, press it and release it about 5 times in total. Primer is a small pump (such as pump action in a bottle of window cleaner) whose function is to suck fuel up into the carburetor from the vessel or floating tank. This allows for easier starting, without requiring multiple pulls of the starter cable to suck fuel into the carburetor.
•     Pull the starter rope until you feel resistance. Let it come back gently and then pull the cable tightly. This should be repeated until the engine starts but no more than 4 times.
•     If the engine has not started at this stage, press the priming button several more times and try to start the engine again by pulling the cable several times. If it does not start, it may have flooded, so leave it for a while for the fuel to evaporate.
•     Once the engine has started and has been running for a few seconds, turn off the choke (If it is a manual control) or change the throttle from the start to the operating position (if there is a start position on the accelerator as described above))

Important!

Check the oil level regularly: the low oil level in an engine can cause premature wear. No oil at all will quickly cause a motor failure.

Safety comes first: Before you work on your lawn mower

Safety comes first: Before you work on your lawn mower

    Important: When working on a pruner, remember that gasoline/gasoline is flammable. Remove all sources of ignition, such as flames, stoves, sparks, cigarettes, or other hot objects in the vicinity when working in the tank or fuel lines. In addition, proper ventilation will prevent buildup of steam. Do not leave wet rags with gas either because they may ignite.

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•     Remove the spark plug or unplug the cord. Before working on the underside of an engine, make sure the controls are off, the spark plug wire is disconnected and the motor has cooled down (if it was previously ripped off). If you are starting to turn the blade, remove the motor cap for absolute safety. In theory, it is possible, even if the plug cable is disconnected and the cylinder of a hot engine is flooded with gas, that the resulting vapor could explode when compressed by the piston, as in a diesel engine, as the blade is rotated during removal or While cleaning the bottom of the platform. Although the engine will not work, it may give a "kick" when turning the blade. This would be enough to cut your fingers or even a whole hand! Maybe it's a remote possibility, but removing the cap will vent the cylinder and prevent this from happening.
•     Keep the carburetor side of the engine up to prevent oil spillage if the mower is side-mounted. The engine oil can also dirty the carburetor and air filter, making it difficult to start. The sump (the tank at the bottom of the engine that contains the oil) is vented to the atmosphere through a deflector/tab valve layout called a vent. Ventilation is necessary so that the air can come in and out of the sump as the piston moves in and out of the cylinder. The baffle prevents the oil droplets from escaping from the vent. In addition, some unburned gases can pass through the piston and into the crankcase. This would eventually cause an increase in pressure without the inclusion of a vent. The vent is sometimes connected to the carburetor through a tube, so any drop of oil that passes through the valve and the unburned gases are sucked into the engine and burned. (A defective vent valve may cause excess oil consumption.) The oil can come out through the vent if the motor rotates sideways with the vent down and the blade turned.
•     Do not forget to drain the fuel tank if the mower is side-mounted. Otherwise, if the fuel level is higher than the vent on the tank cap, it may begin to drip. You can collect the gas in a jug or other suitable container (do not use one made of polystyrene that dissolves in gas). Alternatively, use a siphon pump designed for this purpose. If there is only a small amount of gas in the tank, then you do not need to do this.

Repair of small engines and four-stroke engines used in other equipment

Repair of small engines and four-stroke engines used in other equipment

While these tips apply to lawnmower engines, they are equally valid for other small four-stroke engines used in gardening equipment such as portable generators, air compressors, welders, pumps, cultivators (for example , Rotary cultivators, commonly known as "Rototiller" and "Rotavator"), Snow Plough, compactors (wackers), cement mixers, etc.

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Two-stroke engine troubleshooting

If you have encountered this page and need information on how to operate a 2-stroke engine (installed on hedge trimmers, string trimmers, chainsaws, leaf blowers, small generators and some lawn mowers), check my solution Troubleshooting Guide: The trimmer will not operate: 2-stroke engine and carburetor troubleshooting.

How does a lawn mower work?

A lawn mower motor is quite simple and basic compared to the one installed in your car, although the principle of operation is the same. In general, this type of engines are single-cylinder and four-stroke (four-cycle) and run on gasoline or "gas", which is known as gasoline outside North America. His formal name is "motor Spirit".
"Four times" means that there are four different phases or cycles by which these engines pass before the process is repeated:

First, fuel flows from the tank to a device called a carburetor (often shortened to carb in the U.S. Or carby in Australia) that mixes a thin mist of gasoline with air to form an explosive mixture.

•     First Stroke (admission): The inlet valve opens and the mixture is sucked into a hollow cylinder in the engine block.
•     2nd Stroke (compression): The inlet valve closes and the mixture is compressed.
•     Third Stroke (Power): The mixture ignites with a spark and burns to generate power. The rapid rise in temperature and pressure forces a piston to descend through the cylinder, and this makes a crankshaft turn to turn the blade.
•     4 º Blow (exhaust): The exhaust valve opens and the burned gases are expelled from the cylinder.

The entire four-stroke process is repeated about twenty times per second when the engine runs at maximum speed.

• 4 stroke engine cycle
• 4-Stroke Motor cycle

Warning!!!

Always read the engine and manual of the mower before starting, operating or servicing your engine. Disconnect the spark cable and ideally remove the plug before cleaning the bottom of the platform or turning the blade
If you're trying to start the motor, check the spark connection. But if you need to clean under the deck or turn the blade, then remove the spark plug first.
If you try to turn on the engine, check the spark connection. But if you need to clean under the platform or turn the blade, first remove the spark plug.